Under the iTunes in the Cloud section, click Manage Devices. (If you haven't associated any devices with your Apple ID, you won't see the Manage Devices section.) Information about each associated device appears. Next to each device, you can see when it associated with your Apple ID.
The real reason why the burp smells so badly is hydrogen sulfide (H2S). If you eat foods that have sulfur proteins in them then you may find yourself burping the H2S, which will smell like rotten eggs. The sulfur reducing microbes in the intestine digest the proteins and release the gas.
Belching or burping is caused by a build up of air in the stomach that has been swallowed, so reducing the amount of air you swallow will reduce the amount you burp. Certain foods can weaken an important valve that's designed to keep food and wind in your stomach.